Azam Sattari; Jafar Mohammadzadeh Milani; Zeynab Raftani Amiri; Ali Pakdin Parizi
Abstract
Introduction: Oat establishes a healthy basis for food products. It has gained relevance in human nutrition because it is one of the few cereals with a high content of soluble fiber namely β -glucan, and is a good source of proteins, vitamins, and minerals (Butt et al., 2008). β-glucan is one ...
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Introduction: Oat establishes a healthy basis for food products. It has gained relevance in human nutrition because it is one of the few cereals with a high content of soluble fiber namely β -glucan, and is a good source of proteins, vitamins, and minerals (Butt et al., 2008). β-glucan is one such polysaccharide that has received much attention from the past few years due to its several health beneficial properties, including the ability to remove free radicals in a way identical to antioxidants (Gardiner, 2000). β-glucan is an unbranched polysaccharide consisting of β-D-glucopyranose units linked through (1→4) and (1→3) glycosidic bonds in cereals and (1→6) glycosidic bonds in fungal sources (Ahmad et al., 2016). β-glucan from different sources vary in their molecular structure, chain conformation, solubility, number of β- (1→3)- or β-(1→6)-linkage, and thus different biological activities (Descroix et al., 2006). β-glucan is regarded as an important functional ingredient to lower serum cholesterol, promote weight management, reduce glycemic response, enhance immune system, besides having a prebiotic effect (Zhu et al., 2016; Shah et al., 2016). β–glucan from barley and oat at a 3 g/day dosage as recommended by FDA would reduce cardiovascular disease risk including a reduction in blood glucose and also has satiety effects. Therefore, in order to meet the demands of people related to diets that have a low glycemic index and antioxidant property, non-starch polysaccharides like β-glucan can be used as an ingredient in the products to develop new functional foods (Lee et al., 2016). Oat grain’s fat content is more than that of wheat and it is full of lipase, lipoxygenase, and other hydrolytic enzymes. Over time, enzymes lead to the hydrolysis of the fats present in the oat that make the rancidity taste. Due to the effect of enzyme activity on the stability of oat flakes, these enzymes need to be deactivated during oat processing. One of the methods for disabling enzymes is a hydrothermal process (Doehlert et al., 2010). In this study, the effect of the hydrothermal process using autoclave on the physical and rheological properties of oat β-glucans at different times and temperatures has been investigated. Materials and methods: In this study, beta-glucan was extracted from oats using the hot water extraction method. Hulled oat grains, it put into the autoclave for hydrothermal processing, at three different temperatures of 110, 120 and 130°Ϲ in two different times (10 and 20 minutes) intervals, to measure the effect of time and temperature on physicochemical and functional and rheological properties of β-glucan. After extraction, the physiochemical and functional properties of extracted β-glucan such as solubility, foaming, foaming stability and rheological properties were tested. In order to measure the moisture, ash and protein content, the standard methods (AOAC, 2005) were used. The fat content of the flour was measured by the standard AACC method 25-30. The starch was determined by polarimetry method. For solubility measurement, according to Betancur-Anoka (2003) method, after preparing 90 ml of 1% w / v solution from each sample β-glucan, it was divided into 3 equal parts. Then each of them was placed in a warm bath of 25, 50 and 75 °C for 30 minutes. After centrifuging for 15 minutes at about 8000 g, 10 ml of the upper clear solution was transferred to an oven at 125 °C to reach a constant weight. Finally, solubility percentage at different temperatures was calculated.The foaming capacity and foam stability were studied using the temelli method (1997). For this purpose, 2.5 g, β-glucans was dissolved in 100 mL distilled water. The resulting solution was mixed vigorously for 2 min using a hand held food mixer at high speed in a stainless steel bowl with straight sides and volumes were recorded before and after whipping. To determine foaming capacity, foams were slowly transferred to a 1000 mL graduated cylinder and the volume of foam that remained after staying at 25 ± 2°C for 2 h was expressed as a percentage of the initial foam volume (Temelli et al. 1997; Ashraf Khan et al., 2016). β -Glucan gum solutions were prepared in duplicate in the desired concentration (1.0% of gum, w/w) using distilled water. The rheological properties of the samples were studied by an Anton Paar Physica Rheometer (Physica, MCR 301, Anton Paar GmbH, Germany), with a parallel plate geometry. Results and discussion: β-glucan obtained from hydrothermal process on oat flour at 120°C for 10 minutes had the highest solubility at 25°C and the lowest solubility at 50°C, and 130°C treatment for 10 minutes had the highest solubility at 75°C from hydrothermal process on oat flour at 120°C for 10 minutes had the highest solubility at 25°C, and the treatment of 110°C for 10 minutes and also the treatment of 120°C for 20 minutes had the highest solubility at 50°C and 75°C. The amount of foam in treatment at 130°C for 10 minutes were lower than other treatments and the treatment at 110°C for 10 minutes had the highest foaming stability. In the study of rheological properties, the effect of shear rate on viscosity showed by increasing the shear rate, viscosity decreased in all samples. β-glucan from hydrothermal process on oat flour at 120°C for 10 minutes, had the highest amount of viscosity. In the temperature sweep the parameters included G′ modulus and G″ modulus, the amount of G′ and G″ in β -glucan sample that extracted from hydrothermal process on oat flour were decreased in all samples. Also, G′ and G″ of extracted β-Glucan from hydrothermal process on oat flour at 120°C for 10 minutes was higher than other treatments. In the frequency sweep, at a lower frequency, the amount of G″ was more than G′, and both of them were increased by an increasing frequency and the amount of G′, G″ and η* at 120°C for 10 minutes was higher than other treatments in the frequency of 1 and 10 (Hz). The results showed that the hydrothermal process had a significant effect on the properties and functional properties of β -glucan. Extracted β -glucan sample at 120°C for 10 minutes had the highest solubility at 25°C, and the sample had the lowest solubility at 50°C. The sample treated at 120°C for 20 minutes had the highest solubility at 75°C. The foaming capacity of the sample at 130°C for 10 minutes was lower than other treatments and the treatment at 110°C for 10 minutes had the highest foaming stability. In the study of rheological properties, the effect of shear rate on viscosity decreased in all samples and the treatment of 120°C for 10 minutes had the highest amount of viscosity. In temperature sweep measurement, the amount of G′ and G″ were decreased in all samples and at 120°C for 10 minutes it had the highest amount of G′ and G″. In the frequency sweep, at a lower frequency, the amount of G″ was more than G′, and both of them were increased by an increasing frequency and the amount of G′, G″ and η* at 120°C for 10 minutes was higher than other treatments in the frequency of 1 and 10 (Hz).
Rahil Rezaei; Morteza Khomeiri; Mahdi Kashani-Nejad; Mostafa Mazaheri Tehrani; Mehran Alami
Abstract
β-d- glucan as a soluble dietary fiber, has many desirable physical and physiological characteristic. In this research the effect of β-d- glucan and aging conditions (Time and Temperature) on some physicochemical and textural properties of frozen soy yogurt was investigated. Three variables ...
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β-d- glucan as a soluble dietary fiber, has many desirable physical and physiological characteristic. In this research the effect of β-d- glucan and aging conditions (Time and Temperature) on some physicochemical and textural properties of frozen soy yogurt was investigated. Three variables including concentration of oat β-d- glucan (0, 1 and 2%), aging time (2, 13 and 24 h) and aging temperature (2, 4 and 6°C) were studied. The results showed that the addition of β-d- glucan to frozen yogurt increased viscosity, overrun, hardness and fat destabilization but the melting resistance and L*value were decreased. In terms of aging conditions, it was revealed that increasing aging time could improve the quality of product whereas higher temperature had an undesirable effect on the quality of frozen soy yogurt. Longer aging time caused an increase in viscosity, hardness, fat destabilization and melting resistance. By increasing aging temperature, fat destabilization, overrun and viscosity were decreased and melting rate was increased. It was concluded that addition of β-d- glucan as a dietary fiber and prolonged aging time at low temperature could adjust textural properties of frozen soy yogurt and improve quality of this frozen dessert.
Baharak Hassas; Leila Nateghi; Alireza Shahab lavasani
Abstract
Introduction: Jug cheese is a kind of hard cheese which traditionally produce from raw milk of cow, sheep and sometimes goat in west part of Iran. Its rippening period passed through the clay jug inside the soil, so it contains some varieties of microorganisms that provide it with specific and unique ...
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Introduction: Jug cheese is a kind of hard cheese which traditionally produce from raw milk of cow, sheep and sometimes goat in west part of Iran. Its rippening period passed through the clay jug inside the soil, so it contains some varieties of microorganisms that provide it with specific and unique sensory properties. However, the transmission of some pathogenic bacteria in this product and its high fat content is very important in terms of general health.Therefore, the general objective(aim) of this study was to investigate the physicochemical, antimicrobial and sensory properties of low-fat jug cheese( produced produced from milk with 1.5% fat) Jug cheese containing Beta-Glucan powder ( 0. 25%, 0.5%, 1%) and menthe longifolia ethanolic extract (0.1, 0.2 and 0.3) and with compare the results with control cheese (produced from milk with 3% fat)during 60 days of ripening. Antibacterial results showed that properties using beta-glucan had no significant effect on the antimicrobial properties of the treatments and The use of ethanolic extract of mentha longifolia and increasing its concentration had significantly in the most extreme of the antimicrobial properties of treatments. According to results after 60 days of storage, the treatments containing 0.3% of Mentha longifolia extract, in comparison to the other treatments and Showed the most extreme decrease in the total count of microorganisms, lactobacillus, mould and yeast, coliforms, esherchia coli and staphylococcus aureus. The physicochemical properties investigation showed that the protein, fat, acidity and nitrogen soluble in water durin the preservation period have increased and pH, tissue hardness of the samples have significantly (p≤0.05) decreased. The results of sensory evaluation of cheese showed that the treatment which contained 0.5% beta-glucan and 0.3% ethanolic extract of mentha longifolia has the highest sensory properties. So using 0.5% beta-glucan and 0.3% ethanolic extract of menthe longifolia in low- fat cheese formulas can produce safe cheese with microbial and optimum texture at standard level.
Materials and Method: Jug cheese was produced from 1.5 fat cow milk obtained from Spoota Food Industries Complex, Urmia, Iran. First, milk was heated at 32-35ºC and cooled at 30ºC, then 0.06% cheese rennet (plant rennet, Cominux, Spain) was added and mixed for 5 minutes. After coagulation (45 min), the cheese was cut into 1*1*1 slices and wrapped in a cloth to be kept in room temperature for 12 hours under 0.1 weight plates for dewatering. Coagulants were impregnated in 3.5% salt solutions (since jug chesses is granular, there was no need to chop the samples). Therefore, the samples were squeezed into jugs and the jug was buried top-down in a 1-meter depth hole. Physicochemical, microbial and sensory properties of samples immediately after they were produced and on day 60 (1440 hours) were measured (Pakbin, 1391). Total protein was determined by macro-kjeldahl method with national standard No. 639. Soluble nitrogen was determined by kjeldahl method. Fat was determined by Gerber's method with national standard No. 366 (Anonymous, 1370). Level of moisture was determined by national standard No. 1753. pH was determined by a MA-Mettler pH-meter and titratable acidity (percentage of lactic acid) was determined by 0.1 normal and phenolphthalein as identifiers using national standard No. 2852 (Anonymous, 1385). Ash from cheese samples was measured by burning and full oxidation of food products in an oven at 550ºC (Khosroshahi, 1387). The Mohr titration method with national standard No. 1809 was used to measure salt in cheese samples (Anonymous, 1356). Tissue hardness (pressure or density) was measured using Universal Instron model 1140 and a probe at a constant speed of 100 mm/min. Compression test of cheese samples was done using a 36mm diameter cylindrical probe (hoseini et al, 1392). To measure number of living microorganism in jug cheese samples. To do so, 1g cheese was chopped with a sterile crucible or a mortar and mixed with 9cc buffered Peptone water. About 0.1cc of the solution was cultivated on a special medium by surface cultivation method. Number of microorganisms was measured by national standard No. 5484 in Kant Agar Plate mediums at 30ºC for 72 hours (Anonymous, 1381). Lactobacillus was measured in an MRS-Bile Agar medium (0.15% bile salt) with national standard No. 17164 at 37ºC for 72 hours (Anonymous, 1392). Molds and yeasts were measured, based on national standard No. 10154, in the YGC Agar medium for 5 days at 25ºC (Anonymous, 1386). To measure total formations, based on national standard No. 11166, a VRBA medium with two-layered pure palet method at 35ºC for 18-24 hours (Anonymous, 1387). E. coli was measured, with national standard No. 5234, in an EC Broth medium at 35ºC for 23 hours (Anonymous, 1394). Staphylococcus aureus was measured, based on national standard No. 6806-1, in a Bird-Parker medium with yolk and potassium tellurite at 37ºC for 48 hours (Anonymous, 1384). Sensory analysis was performed by 9 trained evaluators using a Five Point Hedonic Method with scales of one (very good), two (good), three (average), four (bad), and five (very bad) for taste, odor, tissue, and overall acceptability (Anonymous, 1387). In order to design the treatments, a completely randomized design with factorial arrangement was used. Treatments were designed with a control sample.To data analyze use Duncan one-way analysis of variance.
Results & Discussion: The results of antimicrobial evaluation showed treatments containing 0.3% ethanolic extract of mentha longifolia compared to other treatments showed the greatest reduction in total count of microorganisms, lactobacillus, mildew and yeast, coliforms, E. coli, Staphylococcus aureus. Thus, results of the study showed physicochemical characteristics the amount of protein, fat, acidity and nitrogen soluble in water increased and pH, moisture and texture hardness of samples significantly decreased (p≤0.05). The evaluation of sensory properties showed that treatment containing 0.5% β-glucan and 0.3% ethanolic extract of mentha longifolia had the highest sensory acceptability. Therefore, the use of 0.5% β-glucan with 0.3% ethanolic extract of mentha longifolia in the formulation of low-fat jug cheese, can be produced safe cheese with microbial and optimum texture at standard level.